The segments of a commutator are subject to a large centrifugal force tending to lift the brush contacting portions of the segments away from the base. Typically there may be a force of 20 kg. on a segment rotating at 19,000 r.p.m.
A known commutator design has a cylindrical base with a collar at one end supporting a tang for connecting to an armature winding. A recess is provided at the junction of the collar and base and tabs on the segment extend into the recess.